Exercise devices have been in use for years. Some typical exercise devices that simulate walking, jogging, or climbing include cross country ski machines, stair climbing machines, elliptical motion machines, and pendulum motion machines.
In many exercise apparatus, the user's foot is constrained during exercise to patterns that may not accurately represent the typical path and/or position of a foot during walking and/or jogging. For example, cross country ski machines may not allow a user to lift the front of his/her foot above a flat plane defined by the top of the pedal or footpad. Elliptical machines may provide inertia that assists in changing directions of the foot pedals, which may make the exercise smoother and more comfortable. Elliptical machines may, however, constrain a user's foot to the mechanically defined elliptical path of the footpads or foot pedals. The elliptical path may be too long for shorter users or too short for taller users. Thus, an elliptical apparatus may not accommodate a variety of users. In addition, a jogging stride is longer than a walking stride so a fixed stride length apparatus may not optimally simulate several different types of exercise activities.
Pendulum motion exercise apparatus may allow variable stride length. The user's feet, however, may be constrained to follow the same arcuate path in both forward and rearward motion. Such motion may not accurately simulate a walking, striding, jogging, or climbing motion. Certain pendulum motion exercise apparatus may have a fixed pendulum length. A fixed pendulum length may not allow for foot lift or vertical amplitude in the motion of the foot, and thus, may not provide naturally accommodating foot motion. Other pendulum motion exercise apparatus may have relatively short pendulum lengths that may not properly accommodate the path of motion of the foot or legs of the human body.